Leqembi/Donanemab Alzheimer's Drug Denied by Insurance

Anti-amyloid therapies for Alzheimer's disease represent one of the most significant advances in dementia treatment in decades — and one of the most contested insurance coverage battlegrounds in recent memory. Leqembi (lecanemab, developed by Eisai and Biogen) and Kisunla (donanemab, developed by Eli Lilly) are monoclonal antibodies that target and remove amyloid-beta plaques from the brain, slowing the progression of early Alzheimer's disease. Both received FDA approval in 2023–2024 after demonstrating statistically significant reductions in clinical decline in Phase 3 trials. Yet coverage remains complicated, particularly under Medicare, where CMS coverage decisions have created a framework that many patients and physicians find restrictive and confusing.

What These Drugs Treat

Leqembi and Kisunla (donanemab) are indicated for adults with early symptomatic Alzheimer's disease — specifically mild cognitive impairment (MCI) or mild dementia — who have confirmed amyloid pathology. They are not indicated for moderate or severe Alzheimer's disease, and they are not effective in patients without amyloid accumulation. The narrow treatment window (early disease with confirmed amyloid) combined with complex monitoring requirements makes access and coverage especially challenging.

Why Insurance Denies Anti-Amyloid Drugs

Medicare coverage restrictions and PET scan requirements. CMS initially covered lecanemab and donanemab under Coverage with Evidence Development (CED), which historically required patients to be enrolled in a qualifying clinical trial or registry. This significantly limited access for the millions of Medicare patients who would not qualify for or seek out trial enrollment. In 2024, CMS updated its position and moved toward Traditional Coverage for FDA-approved anti-amyloid therapies, but coverage frameworks continue to evolve and vary by plan, creating ongoing access uncertainty.

PET scan requirement for amyloid confirmation is both a clinical necessity and an insurance access barrier. Amyloid PET scans (using tracers like florbetapir or flortaucipir) are required to confirm amyloid pathology before starting therapy — the drugs simply do not work without amyloid to target. However, amyloid PET scans are expensive and have historically had limited Medicare coverage. Under the Inflation Reduction Act and subsequent CMS rule changes, coverage for one amyloid PET scan per lifetime has been established for Medicare patients — but navigating this coverage and getting the scan authorized prior to starting therapy adds time and complexity.

Prior Authorization Denied: How to Appeal" class="auto-link">Prior authorization is required and involves extensive documentation: confirmed Alzheimer's diagnosis, cognitive assessment results (such as MMSE or MoCA scores), amyloid confirmation via PET or CSF biomarkers, APOE4 genotype testing (to assess ARIA risk), MRI results (required before initiation), and prescriber specialty confirmation (prescriptions must come from a neurologist, geriatrician, or psychiatrist specializing in dementia).

ARIA monitoring requirements — amyloid-related imaging abnormalities — are a significant safety consideration. Both drugs can cause brain swelling (ARIA-E) or microhemorrhages (ARIA-H) that require MRI monitoring. ARIA monitoring requires serial MRIs, and insurers must cover this monitoring as a condition of covering the drug. Some denials occur because the required monitoring infrastructure is not established or documented.

APOE4 homozygous patients face higher ARIA risk and may be denied by some plans that consider the risk-benefit ratio unfavorable for this genetic subgroup, though physicians and patients have the right to make individualized treatment decisions.

Commercial insurance coverage is separately determined by each plan and varies widely. Some commercial plans have been slow to add Leqembi and Kisunla to formulary following FDA approval, resulting in non-coverage denials for commercially insured patients.

How to Appeal a Leqembi or Kisunla Denial

Confirm the coverage framework first. Before appealing, determine whether your insurer's denial is based on a CED/clinical trial requirement, a prior authorization deficiency, or a formulary exclusion. The appeal strategy differs significantly for each.

Submit complete diagnostic documentation. Your appeal should include: formal Alzheimer's diagnosis documentation, MMSE or MoCA cognitive assessment scores confirming mild impairment or mild dementia (not moderate or severe), amyloid PET scan report confirming amyloid pathology, APOE4 genotyping results with your physician's assessment of ARIA risk, baseline brain MRI report, and your neurologist's or dementia specialist's clinical summary.

Challenge CED restrictions with current CMS policy. If your Medicare plan is citing a clinical trial requirement that has been superseded by updated CMS Traditional Coverage, cite the current CMS coverage determination and provide the publication date. CED requirements that have been lifted cannot be lawfully applied to deny coverage for FDA-approved indications under Traditional Coverage.

Document that disease stage qualifies. Both drugs are indicated for early symptomatic disease. If an insurer denies because they question whether your disease stage is appropriate, provide cognitive testing scores, clinical notes describing symptom onset and functional status, and any neuropsychological testing documenting the MCI or mild dementia diagnosis.

Engage the Alzheimer's Association. The Alzheimer's Association (alz.org) has significant resources for patients navigating Leqembi and donanemab coverage issues, including a helpline (1-800-272-3900) that can connect patients with care consultants familiar with insurance access challenges for anti-amyloid therapies.

Patient Assistance Programs

Eisai and Biogen offer patient assistance programs for Leqembi (lecanemab). Eli Lilly offers the Lilly Cares Foundation for Kisunla (donanemab). Contact the respective manufacturer's patient assistance line for current program details and eligibility criteria.

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